This research project is engaged in investigating the transport and excretion of certain endogenous acids in hypertensive and normotensive dogs and monkeys. Three of the acids are essental for human health and thus are ccnsidered vitamins--ascorbic acid, nicotinic acid (niacin), and p-aminobenzoic acid (PABA). In the next project period, we will be concentrating on understanding why the endogenous acid urate is retained by the kidney in hypertension. The hyperuricemia often in hypertension has been established to result from a decreased excretion of urate and not increased biosynthesis. There is reason to believe that other endogenous organic acids are formed in hypertension and these are competing with the renal secretion of urate. The likeliest contender is lactic acid since plasma concentrations are often elevated in hypertension and since lactic acid decreases excretion of urate in some species. We want to look into the entire problem of th modification of urate excretion by lactate. Primarily, Cebus monkeys will be used since these, like man, excrete uric acid as the end product of purine metabolism. The renal handling of uric acid by the Cebus monkey seems very similar to that seen in humans and therefore this species has been used in many problems dealing with urate in the past five years. Another phase of this research will be to attempt to develop a state of permanent hypertension in the Cebus monkeys and then to determine whether any organic acids can be detected in elevated quantities in their plasma. We will first look at plasma concentrations of lactate. Increased quantities of other potential urate inhibitors will be the object of investigation. It will also be desirable to see how the hypertensive monkeys excrete the endogenous acids which are vitamins and to compare their excretion characteristics with normotensive monkeys.